Engine piston

Abstract

This invention relates to the shape of a skirt below the piston head of a piston in an engine cylinder and continuous with it. The skirt has a basic configuration comprising at least two type of elliptical horizontal cross-section with a short axis parallel to said piston pin, and a barrel-shaped vertical cross-section smaller at its top and bottom. A T-shaped projection is also provided on the lateral surfaces of the skirt corresponding to the two ends of the long axis of said ellipse, this projection consisting of a vertical piece and two side pieces situated on either side of the vertical piece. When the engine is running, the skirt comes into contact with the inner surface of the cylinder via this projection. The vertical section of the lower part of the skirt from below the lower edge of the two side pieces to the lower edge of the skirt is inclined toward the inside of said barrel-shaped vertical section so that the skirt is joined smoothly to the projection below the two side pieces. Accumulation of pressure on the edge of the projection is thereby prevented, which reduces frictional resistance and prevents wear between the piston and the cylinder.

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A piston adapted to slide in an engine cylinder having a piston head with a circular cross-section, a skirt formed below said piston head and continuous with it, a piston pin traversing said skirt and a connecting rod connected to this pin, wherein said skirt has a basic configuration comprising at least two types of elliptical horizontal cross-section with a short axis parallel to said piston pin, and a barrel-shaped vertical cross-section smaller at its top and bottom, said skirt has an approximately "T"-shaped projection on the lateral surfaces of said skirt corresponding to the two ends of the long axis of said ellipse, said projection consisting of a vertical piece and two side pieces situated on either side of said vertical piece, and a vertical section of the lower part of said skirt from below the lower edge of said two side pieces to the lower edge of said skirt is inclined toward the inside of said barrel-shaped vertical section so that said skirt is joined smoothly to said projection below said two side pieces. 
     
     
       2. A piston adapted to slide in an engine cylinder as defined in claim 1, wherein the eccentricity of the elliptical horizontal cross-section passing through the center of said piston pin is smaller than the eccentricity of the elliptical horizontal cross-section below said piston pin. 
     
     
       3. A piston adapted to slide in an engine cylinder as defined in claim 1, wherein the barrel-shaped vertical cross-section of said skirt from which said two side pieces project has a smaller a radius of curvature than the barrel-shaped vertical cross-section of said skirt from which said vertical piece projects. 
     
     
       4. A piston adapted to slide in an engine cylinder as defined in claim 1, wherein the shortening of the diameter of said barrel-shaped vertical cross-section is greater nearer the top closer to said piston head.